System and method for a power line modem

ABSTRACT

In accordance with an embodiment, a method of operating an electronic system includes detecting an incoming transmission on a power line, and modifying a switching behavior of a switched-mode power supply coupled to the power line upon detecting the incoming transmission. Modifying reduces the level of interference produced by the switched-mode power supply.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.13/656,369, filed Oct. 19, 2012, now allowed, which application isincorporated herein by reference in its entirety.

BACKGROUND

1. Technical Field

This invention relates generally to electronic circuits, and moreparticularly to a system and method for a power line modem.

2. Description of the Related Art

Digital and analog data communications over conventional utility andpremises electric power lines is an established method forpoint-to-point and point-to-multipoint communications between devices.In such communications, a communication signal carrying data issuperimposed on a 50 to 60 Hz alternating current (AC) power line usinghigher frequencies. A central computer may use such a power linecommunications system to control remote power applications, to monitorremote utility usage, or to support energy conservation. For example,the central computer may control the operation of heaters,air-conditioners, electric lighting and the like. The power linecommunications system may also be used to support high-speed broadbanddata to support Internet, multimedia and home entertainment systems,using a power line communication network such as IEEE 1901, IEEEP1901.2, HomePlug GP/AV/AV2/1.0, G.hn, G.hnem, and other similartechnologies.

The throughput of a power line communication link, such as a linkbetween two modems or network nodes, may be affected by environmentalelectrical interference and may suffer degradation when the level ofinterference is high. For example, when an appliance, such as atelevision or computer, is attached to the power line in the generalproximity of the point where the modem is attached to the same powerline, switching noise from the switched-mode power supply of theappliance may create disturbances on the power line that reduce thesignal to noise ratio and the bandwidth available to the power linemodem. In some cases, these disturbances may be exacerbated when thereis high attenuation of data signals superimposed on the power line.

BRIEF SUMMARY

In accordance with an embodiment, a method of operating an electronicsystem includes detecting an incoming transmission on a power line, andmodifying a switching behavior of a switched-mode power supply coupledto the power line upon detecting the incoming transmission. Modifyingreduces the level of interference produced by the switched-mode powersupply.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

For a more complete understanding of the present disclosure, and theadvantages thereof, reference is now made to the following descriptionstaken in conjunction with the accompanying drawings, in which:

FIGS. 1 a-c illustrate embodiment power line communication nodes;

FIG. 2 illustrates an embodiment backlit display;

FIG. 3 illustrates an embodiment power line communication system;

FIGS. 5 a-b illustrate example spectra of a switched-mode power supply;

FIG. 6 illustrates an embodiment waveform diagram showing a relationshipbetween a received packet and embodiment control signals; and

FIG. 7 illustrates a flowchart of an embodiment method.

Corresponding numerals and symbols in different figures generally referto corresponding parts unless otherwise indicated. The figures are drawnto clearly illustrate the relevant aspects of embodiments of the presentinvention and are not necessarily drawn to scale. To more clearlyillustrate certain embodiments, a letter indicating variations of thesame structure, material, or process step may follow a figure number.

DETAILED DESCRIPTION

The making and using of embodiments are discussed in detail below. Itshould be appreciated, however, that the present invention provides manyapplicable inventive concepts that may be embodied in a wide variety ofspecific contexts. The specific embodiments discussed are merelyillustrative of specific ways to make and use the invention, and do notlimit the scope of the invention.

The present disclosure will be described with respect to embodiments ina specific context, namely a system and method for a power line modem.Embodiments of this invention may also be applied to other circuits andsystems, such as, but not limited to, communication systems andswitched-mode power supplies.

Generally, embodiments of the invention effect operating parameters of aswitched-mode power supply in such a way that the switched-mode powersupply creates less power line noise. By creating less power line noise,a higher SNR and/or more bandwidth is available to the power linecommunications system. These operating parameters may be modified when apacket is received by the power line modem. For example, when a powerline modem detects a preamble of a received packet, one or moredifferent actions may be taken to reduce the effect of power line noiseon a received data transmission. When the modem detects the end of thepacket, the power supply and appliance may be returned to normaloperation. In some embodiments, these packets may be divided andtransmitted and received as pieces in multiple frames.

In an embodiment, frequency fluctuation of the switched-mode powersupply may be suspended. This frequency fluctuation refers to harmonicspreading used by many power supplies to reduce peak harmonic energy. Bysuspending this frequency fluctuation, more bandwidth could be availablefor power line communications. In multi-carrier systems, such as OFDM,carriers that occupy frequencies between center frequencies of harmonicscan be utilized for data transmission with a higher SNR.

Another embodiment method to reduce the effect of power line noise onreceived data is by reducing the DC power supply power output of theswitched-mode power supply. By reducing the power output, the overalllevel of switching energy is reduced. This lowers that disturbance noisefloor and allows the more bits to be transmitted. For example, in someembodiment OFDM systems, a more complex constellation and/or lessaggressive coding may be used in the presence of a higher SNR to improvethroughput. In other embodiment OFDM systems, a smaller constellationand more aggressive coding scheme can be maintained in order to realizelower error rate, for example, in high QoS applications.

In an embodiment, this reduction in DC power supply output may beeffected by reducing the load on the switched-mode power supply. Anappliance coupled to the switched-mode power supply may be placed into amomentary low-power mode for the duration of the received packet. Forexample, in a LED backlit television set, the LED backlight may be shutoff or its intensity reduced during the duration of the received packet.Because the length of a received packet is very short, for example500us, the reduction in illumination may be imperceptible by the humaneye. In some embodiments, power is reduced by 10% to 20%.

In an embodiment, information related to the status of the renderingdevice, such as a television set, decisions can be made regarding thelevels of power reduction in order to take into account artifactsstemming from power reduction, such as visible flicker effects. As such,embodiment power reduction methods may provide a more substantial powerreduction during these times when visual artifacts are less pronounced,for example, when an arrival of a transmission occurs during atransition from one image to another, or when a dark image is displayed.

A reduction in the DC power supply output may also be implemented bymomentarily suspending switching on the DC power supply. During theshort period of time that the modem receives a packet, switching issuspended on the DC power supply. Capacitors coupled to the DC output ofthe switched-mode power supply may used during this time to supply theappliance with power. Such an embodiment may be applied, for example, toconsumer audio applications. While an audio system is constantlyreceiving audio packets and, in some cases in bursts of audio packets,power requirements of an audio amplifier greatly depend on the patternof the audio signal that may include periods of high and low audiointensity. During such low intensity periods, a greater degree of poweroutput reduction is possible. In some embodiments, data receive andtransmit operations may be synchronized with the audio pattern renderedby the device. As an example, a power line communication node coupledwith an audio system may schedule transmissions during the periods ofhigh audio intensity, and receive transmissions during periods of lowaudio intensity. Consequently, such a power line communication block mayconsume more power during data transmission, and less power during datareception. By handling transmissions during quieter periods of renderedaudio, a device may reduce its peak power consumption. Such embodimenttransmission schemes may also be applied to other media types, such asvideo. For example, transmissions may be performed during quieterperiods of video data or other media. Such quieter periods may representperiods in which picture has a lower light intensity. In someembodiments transmission and receiving operations may be scheduled suchthat that the pattern of said operations is synchronized with the knownor detected pattern of the intensity of the content rendered by thedevice. The content may be audio, video, light emission, or othercontent.

In embodiments systems having transmission structures that combinereceive and transmit operations, sufficient power may be provided to atarget device while power savings modes are being asserted. For example,in HomePlug AV a receive operation is typically followed by atransmission of an acknowledgement (ACK) signal. As such, periods duringwhich a switched-mode power supply operates in a reduced power mode isfollowed by periods during which the switched-mode power supply mayoutput more power. In some embodiments, these ACK signals may bedeferred or delayed in order to give the switched-mode power supply anopportunity to recover from a reduced power mode.

The DC switching behavior of the DC power supply may be further modifiedin other ways. For example, in an embodiment, the transmission frequencyof the power line communication device may be coordinated with aswitching frequency of the DC power supply, such that the transmissionfrequency of the power line communication device does not fall on aharmonic or other spurious tone generated by the DC power supply. In oneembodiment, the both the transmission frequency and the DC power supplyswitching frequency are scheduled according to pre-programmed frequencyhops. By operating the communication system according to apre-programmed frequency hop pattern, spurious energy emitted by the DCpower supply may be kept below a particular threshold to comply withemissions standards as well as reducing interference with datacommunications. Power line communication systems such as HomePlug AV asan example allow “slicing” of the line cycle into multiple timeintervals during which a unique tone map (configuration of modulationdensity per carrier) may be used. The frequency hop pattern serves tospread harmonic energy of the DC switched-mode power supply over a widerbandwidth, thereby reducing the peak power spectral density of emissionsaveraged over time, and the relationship between the hopped switchingfrequencies to the hopped data transmission frequencies avoidsinterference between the switching of the DC power supply and anincoming or outgoing data transmission. In some embodiments, thisfrequency hop pattern may be set to prevent average emissions fromexceeding a threshold.

In an embodiment, the pre-programmed frequency hops. In an embodiment,the determination and scheduling of frequency hops may be performedaccording to a preset schedule, according to a synchronized pseudorandomprocess using, for example, a linear feedback shift registers, afrequency hop scheduled programmed in a lookup table, or by anothersynchronized process known in the art. In some embodiments, an adaptiveprocess may be used that detects problematic frequencies and omits theseproblematic frequencies in the hopping schedule. For example, in someembodiments, the RF frequencies may be scanned for pre-existing spuriousemissions from other sources, or for frequencies having high attenuationand/or poor propagation properties due to multipath interference.Frequency hopping may be scheduled such that the interference producedby the switched-mode power supply falls onto frequencies that are highlyattenuated, have high noise levels, and/or may be unsuitable forcommunication. In some embodiments, channel quality-based frequencyhopping may be performed in conjunction with existingstandards-compatible channel quality measurement schemes. For example,according to the HomePlug AV standard, a channel analysis may beperformed when a link is established between two devices. This channelanalysis provides a list of possible modulation densities for eachcarrier. In an embodiment directed toward HomePlug AV and similardevices, the results of the channel analysis may be used to determine afrequency hopping schedule. For example, frequencies associated withcarriers identified as having a low modulation density may be selectedas the list of preferred frequencies, and hoping will be managed in suchway that the harmonics of the switching power supply will fall on thesepreferred frequencies. In some embodiments, a table listing the outputof the channel analysis may be used as an input to identify the relativeperformance of candidate frequency carriers, for example, by ranking thecandidate frequency carriers according to channel quality. As such, aneffective frequency hopping schedule may be determined with lowprocessing overhead. It should be appreciated that in other embodimentsdirected toward other standards, existing channel analysis resources mayalso be used.

In an embodiment, the switched-mode power supply may operate accordingto default frequency spreading schedule, and then synchronize to afurther spreading schedule and/or resynchronize to an existing spreadingschedule when the power line communications modem is about to transmitand/or receive data.

Embodiments of the present invention may be directed toward devices thatmay be configured to operate on a power line network, for example,consumer electronic devices, multimedia devices and television sets,computing devices, appliances such as refrigerators, washing machines,dryers, HVAC equipment and lighting systems such as LED or CFL lighting.Devices, such as computing devices may use the power line network tocommunicate with or to control other devices and appliances on the powerline network and/or to access a local area or wide area network, such asthe Internet. Appliances and lighting systems may use the network, forexample, to coordinate power management as described in U.S. patentapplication Ser. No. 13/461,173 entitled “System and Method for anIntelligent Power Controller” filed on May 1, 2012, which has beenincorporated by reference herein in its entirety.

FIG. 1 a illustrates embodiment system 100 having modem 102,switched-mode power supply 104 and a target device 106. As shown,switching power supply 104 is coupled to AC power line 108 via powerinterface 114, and modem 102 is coupled to communication link 110 viacommunication interface 112. Target device 106, which may include anappliance or other device, receives power from switched-mode powersupply 104 via DC power bus 116. Communication link 110 may beimplemented using a wired local area network connection such as FastEthernet, a wireless local area network, such as an 802.11 WiFi orZigBee network, or using a power line communication network such as IEEE1901, IEEE P1901.2, HomePlug GP/AV/AV2/1.0, G.hn, G.hnem, and othersimilar technologies. Alternatively, other network technologies orcommunication links may be used, such as Ethernet and the like. In thecase of a power line communication network, such as an IEEE 1901network, modem 102 may be a power line modem and communication link 110may be physically implemented using the same physical line as

AC power line 108.

When modem 102 detects an incoming transmission, Spectral Control signal118 is activated, thereby causing the switched-mode power supply tomodify its operation in order to provide less noise and/or morebandwidth for the power line modem. Alternatively, Spectral Control 118may cause switched-mode power supply 104 to synchronize a frequencyhopped switching frequency pattern with the transmission or receptionfrequency used by modem 102. Modem 102 may also signal target device 106to operate in a low power mode during the duration of the reception of areceive packet or a transmission of a transmit packet via Power Controlsignal 120.

FIG. 1 b illustrates embodiment system 130 in which preamble detector132 is coupled to communication link 110 via communication interface112, to switched-mode power supply via Spectral Control signal 118, andto target device 106 via power control signal 120. In an embodiment,preamble detector 132 detects the preamble of incoming data packets andplaces switched-mode power supply and target device 106 in anappropriate state. In some embodiments, preamble detector 132 may have asubset of the functionality of modem 102 shown in FIG. 1 a. In someembodiments, power mode selection methods may be applied to transmissionand packet detection, as described in U.S. Pat. No. 8,115,605, entitled,“Power line communications device in which physical communicationsprotocol layer operation is dynamically selectable,” which applicationis incorporated herein by reference in its entirety.

FIG. 1 c illustrates embodiment system 150 configured to operate using afrequency hopped sequence. In an embodiment, modem 152 has frequency hopcontroller 156, and switched-mode power supply 154 has frequency hopcontrol 158. In some embodiments, modem 152 asserts sync signal 160 whenan incoming packet is detected.

When switched-mode power supply detects sync signal 160, a predeterminedfrequency hop sequence is commenced, such that frequency controlsequences generated by frequency hop controller 156 and frequency hopcontroller 158 are synchronized. Frequency hop controllers 156 and 158may be further synchronized with a frequency hop controller of thetransmitting node from which modem 152 receives its data. In alternativeembodiments, frequency hop controllers 156 and 158 may be furthersynchronized at times during which modem 152 is not receiving data, forexample, during idle periods and/or during data transmission periods.

FIG. 2 illustrates block diagram of an LED backlit display system 200that includes backlit display 202 coupled to modem 214. In anembodiment, LED backlit display system 200 has backlight controller 204coupled to display 206 via signal 218. Display 206 includes LEDbacklight 208 and pixel display 210. Switched-mode power supply 212 iscoupled to AC power line 108 via power interface 222, and modem 214 iscoupled to communication link 110 via communication interface 224, toswitched-mode power supply 212 via Spectral Control signal 220, and tobacklight controller 204 via power control signal 216. In someembodiments, about 90% of the power being consumed by the switched-modepower supply is provided to the LED backlight. When modem 214 detects areceived transmission, the operation of the switched-mode power supplyis modified to produce less switching noise by momentarily reducing theintensity of the light LED backlight via the backlight controller. Infurther embodiments, switched-mode power supply 212 may operate with afrequency hopped switching frequency scheme as described above. Forexample, switched-mode power supply 212 may synchronize its hoppedswitching frequency scheme when spectral control signal 220 indicates anincoming received packet and/or an outgoing transmitted packet.

FIG. 3 illustrates a block diagram of embodiment power linecommunications network 300 that includes a number of lighting nodes 302,networked appliance 304, HVAC system 306, local controller 308 (such asa user terminal), power meter 314, solar panel controller 312, andenergy storage device 316. Energy storage device 316 may include abattery, but may also represent an electric car that consumes power fromAC power line 108 during some time periods, and/or makes power availableto the network via AC power line 108 during other time periods. Thedevices coupled to AC power line 108 communicate with each other overcommunication link 110, which may be implemented using a wired orwireless network medium as described with respect to FIG. 1 a above. Itshould be understood that network 300 is just one of many examples of anembodiment power line communications network, and that in alternativeembodiments, any number of lighting nodes 302 or other devices, may becoupled to power line 108. Alternatively, power line 108 may beimplemented using a DC power line, or other power distribution typeincluding wireless power.

FIG. 5 a illustrates an example output spectrum of a switched-mode powersupply operating in a “spread spectrum” state, which may be implementedusing frequency hopping spread spectrum techniques, direct sequencespread spectrum techniques, pulse position modulation of the switchingsignal for the switched-mode power supply and/or other techniques knownin the art. Here, a wideband flat spectrum is shown extending fromaround a switching frequency of a power supply to over 50 MHz. It shouldbe understood that other switching noise bandwidths and spectral shapesmay also be possible.

FIG. 5 b illustrates example output spectra of a switched-mode powersupply without spreading of the harmonic spectrum with and without theactivation of an embodiment reduced power mode. FIG. 5 b furtherillustrates carriers available for OFDM power line communications. Insome embodiments, the available OFDM bandwidth may be used by selectingOFDM tones that are not coincident with harmonic power line disturbancetones.

FIG. 6 illustrates a waveform diagram 600 showing an example receivedpacket and an example timing relationship between the received packetand embodiment control signals. In an embodiment, Disable PWM Spreadingsignal 604 and Reduced Power mode signal 606 becomes asserted after thecompletion of preamble 602 of incoming Decoded Data. At the completionof End of Transmission indicator 608, Disable PWM Spreading signal 604and Reduced Power mode signal 606 is de-asserted.

FIG. 7 illustrates flow chart 700 of an embodiment method. In step 702the existence of a preamble is detected. This preamble may be similar,for example, to preamble 602 shown in FIG. 6. Once the preamble has beendetected, harmonic spreading is disabled in the switched-mode powersupply during step 704. In step 706, a low power mode may be enabledwithin a target device coupled to the modem and the switched-mode powersupply. In some embodiments of the present invention, step 704 or 706may be omitted depending on the particular embodiment and itsrequirements. Next, in step 708, the end of transmission segment isdetected. When the end of transmission of the data segment is detected,harmonic spreading is enabled in step 710 and the low-power mode isdisabled in step 712.

In accordance with an embodiment, a method of operating an electronicsystem includes detecting an incoming transmission on a power line, andmodifying a switching behavior of a switched-mode power supply coupledto the power line upon detecting the incoming transmission. Modifyingreduces the level of interference produced by the switched-mode powersupply, and may be implemented, and may improve the receivingcapabilities of the electronic system as a result. In some cases,modifying the switching behavior is achieved by disabling harmonicspreading.

In an embodiment, the method includes reducing a power output of theswitched-mode power supply upon detecting the incoming transmission.Reducing the power output may include reducing a power consumption of aload coupled to a DC output of the switched-mode power supply. Such areduction in power consumption in the load may include reducing a powerconsumption of a backlight of a video display device. In an embodiment,reducing the power consumption of the backlight includes reducing thepower consumption of the backlight proportional a darkness of acurrently displayed image, and further reducing the power consumption ofthe backlight when the incoming transmission occurs during a transitionfrom a first image to a second image.

In other embodiments, reducing the power consumption of the loadincludes reducing a power consumption of a media device. For example,the media device may be an audio device, and the power consumption ofthe audio device is reduced by reducing the power consumption of theaudio device inversely proportional to an amplitude of an audio signalrendered by the audio device. Furthermore, data transmissions may besynchronized according to the media signal rendered by the media device.The method may further include determining a pattern of contentintensity of the media signal, and synchronizing the data transmissionsaccording to the determined pattern.

In an embodiment, an acknowledgement (ACK) signal is transmitted inresponse to receiving the incoming transmission. The method may furtherinclude reducing a power output of the switched-mode power supply upondetecting the incoming transmission, increasing the power output of theswitched-mode power supply after the incoming transmission has beenreceived, and delaying transmitting the ACK signal until afterincreasing the power output.

In accordance with a further embodiment, a system includes atransmission detector that is configured to be coupled to a power line,such that the detector is configured to detect a received datatransmission on the power line. The transmission detector may include afirst output configured to be coupled to a switched-mode power supply,and the first output may be configured to signal the switched-mode powersupply to modify switching to reduce the levels of interference of thepower supply. The transmission detector may include a power line modem,and may be configured to detect a preamble of an incoming data packet.

The transmission detector may further include a second output configuredto be coupled to a load coupled to the switched-mode power supply, suchthat the second output is configured to signal the load to reduced powerconsumed from the switched-mode power supply.

In accordance with another embodiment, system includes a transmissiondetector configured to be coupled to a power line, and is configured todetect a received data transmission on the power line and indicate via afirst output signal that a data transmission is being received. Thesystem also includes a switched-mode power supply coupled to the firstoutput signal that is configured to be coupled to the power line. Theswitched-mode power supply modifies its switching behavior when thefirst signal indicates a data transmission is being received, such thatmore channel resources are available for the data transmission beingreceived.

In some embodiments, the switched-mode power supply disables harmonicspreading when the first signal indicates that a data transmission isbeing received. Furthermore, wherein the transmission detector may beconfigured to detect a received transmission by detecting a preamble ofthe received transmission before the received transmission has beencompletely received.

In accordance with a further embodiment, a method of operating anelectronic system includes detecting a start of an incoming datatransmission on a power line using a first receiver, determiningmodulation densities associated with one or more carriers on which datais being received, and setting a switching behavior of a switched-modepower supply coupled to the first receiver based on the determining. Themethod may also include setting the switching frequency of the powersupply, such that harmonics produced by the power supply fall onfrequencies associated with the carriers that have the lowest modulationdensities. Setting the switching behavior of the switched-mode powersupply may include adjusting a switching frequency of switched-modepower supply to avoid interference with the received data transmission.

In an embodiment, the switching frequency of the power supply may be setaccording to a hop sequence. Accordingly, outgoing data may betransmitted using a transmission frequency based on the hop sequence.For example, the method may include determining the hop sequence bymeasuring or extracting an already measured channel quality of aplurality of candidate frequency carriers, ranking the candidatefrequency carriers according to measured channel quality, and selectingcandidate frequency carriers having a low rank for the hop sequence.

In accordance with another embodiment, a system includes a receiver anda switched-mode power supply control module coupled to the receiver.Some embodiments may also include a switched-mode power supply. Thereceiver may be configured to be coupled to a power line, receive anincoming data transmission on a power line, and determine a receptionfrequency of the received data transmission. The switched-mode powersupply control module may be configured to modify a switching behaviorof a switched mode power supply based on the determined receptionfrequency. In addition, the receiver may be configured to determine thereception frequency based on a predetermined hop sequence that may bedetermined according to a channel profile, such that harmonics ofswitching frequencies of the switched mode power supply are configuredto fall on frequencies associated with carriers having lowest modulationdensities.

The system may further include a transmitter configured to transmit anoutgoing data transmission using a transmission frequency based on thepredetermined hop sequence. In some embodiments, the switched-mode powersupply control module may be configured to modify the switching behaviorby adjusting a switching frequency of the switched-mode power supply toavoid interference with the received data transmission.

Advantages of embodiments include the ability to achieve high qualitypower line communications with appliances that generally emit highlevels of power line interference. Another advantage includes theability to greatly improve throughput and available bandwidth for powerline communications, thereby providing better performance.

Further advantages of some embodiments include an improvement in theoverall power management of a device by reducing the peak powerconsumption. For example, a power line communication block of a systemmay consume more power during data transmission, and less power duringdata reception. By handling transmissions during quieter periods ofrendered audio, a device may reduce its peak power consumption.

The following U.S. Patent Application Publications and U.S. Patents areincorporated herein by reference in their entirety: U.S. Pat. No.6,917,888, entitled, “Method and system for power line network faultdetection and quality monitoring;” U.S. Pat. No. 7,106,177, entitled,“Method and system for modifying modulation of power line communicationssignals for maximizing data throughput rate;” U.S. Pat. No. 7,193,506,entitled, “Method and system for maximizing data throughput rate in apower line communications system by modifying payload symbol length;”U.S. Pat. No. 7,369,579, entitled, “Method and system for timingcontrolled signal transmission in a point to multipoint power linecommunications system;” U.S. Pat. No. 7,683,777, entitled, “Method andsystem for audio distribution in installations where the use of existingwiring is preferred;” U.S. Pat. No. 7,804,673, entitled, “Intelligent,self-aware powerline conditioning and communication node;” and U.S. Pat.No. 8,115,605, entitled, “Power line communications device in whichphysical communications protocol layer operation is dynamicallyselectable.” Systems and methods described in the above mentioned U.S.Patents can be applied to embodiments described herein.

It will also be readily understood by those skilled in the art thatmaterials and methods may be varied while remaining within the scope ofthe present invention. It is also appreciated that the present inventionprovides many applicable inventive concepts other than the specificcontexts used to illustrate embodiments. Accordingly, the appendedclaims are intended to include within their scope such processes,machines, manufacture, compositions of matter, means, methods, or steps.

The various embodiments described above can be combined to providefurther embodiments. All of the U.S. patents, U.S. patent applicationpublications, U.S. patent applications, foreign patents, foreign patentapplications and non-patent publications referred to in thisspecification and/or listed in the Application Data Sheet areincorporated herein by reference, in their entirety. Aspects of theembodiments can be modified, if necessary to employ concepts of thevarious patents, applications and publications to provide yet furtherembodiments.

These and other changes can be made to the embodiments in light of theabove-detailed description. In general, in the following claims, theterms used should not be construed to limit the claims to the specificembodiments disclosed in the specification and the claims, but should beconstrued to include all possible embodiments along with the full scopeof equivalents to which such claims are entitled. Accordingly, theclaims are not limited by the disclosure.

1. A method to reduce interference produced by a switched-mode powersupply in an Internet-enabled device receiving power from a 50 to 60 Hzalternating current (AC) power line, comprising: receiving acommunication signal superimposed on the AC power line, thecommunication signal carrying Internet data; detecting a preamble of thecommunication signal; upon detecting the preamble, reducingcommunication interference by automatically modifying an operating modeof the switched-mode power supply.
 2. The method of claim 1, whereinmodifying the operating mode of the switched-mode power supply includesat least one of disabling harmonic spreading of the switched-mode powersupply, reducing a power output of the switched-mode power supply, andsuspending frequency fluctuation of the switched-mode power supply. 3.The method of claim 2, wherein reducing the power output of theswitched-mode power supply includes reducing a power consumption of aload coupled to a DC output of the switched-mode power supply.
 4. Themethod of claim 2, wherein reducing the power output of theswitched-mode power supply includes at least one of reducing a powerconsumption of a backlight of a video display device and reducing apower consumption of an audio device.
 5. The method of claim 4, whereinreducing the power consumption of the backlight of the video displaydevice comprises: reducing the power consumption of the backlightproportional to a darkness of a currently displayed image; and furtherreducing the power consumption of the backlight when the incoming datatransmission occurs during a transition from a first image to a secondimage.
 6. The method of claim 4, wherein reducing the power consumptionof the audio device comprises: reducing the power consumption of theaudio device inversely proportional to an amplitude of an audio signalrendered by the audio device.
 7. The method of claim 4, wherein reducingthe power consumption of the audio device comprises: synchronizing datatransmissions according to an audio signal rendered by the media device.8. The method of claim 4, wherein reducing the power consumption of theaudio device comprises: determining a pattern of content intensity ofthe media signal; and synchronizing data transmissions according to thedetermined pattern.
 9. The method of claim 2, wherein reducing the poweroutput of the switched-mode power supply comprises: supplementing thepower output of the switched-mode power supply with power from at leastone capacitor.
 10. The method of claim 1, wherein the Internet-enableddevice is a home appliance, and wherein modifying the operating mode ofthe switched-mode power supply comprises: reducing a power output of theswitched-mode power supply upon detecting the preamble; increasing thepower output of the switched-mode power supply after an incoming datatransmission has been received; and delaying transmitting an ACK signaluntil after increasing the power output.
 11. An Internet-enabledappliance, comprising: a switched-mode power supply arranged to receivepower from a 50 to 60 Hz alternating current (AC) power line; and apower line modem arranged to pass Internet communications via the ACpower line, the power line modem arranged to direct an automaticmodification of an operating mode of the switched-mode power supply upondetection of a preamble of a communication signal passed on the AC powerline.
 12. The Internet-enabled appliance of claim 11, comprising: atransmission detector configured to detect the preamble.
 13. TheInternet-enabled appliance of claim 11, wherein modification of theoperating mode of the switched-mode power supply is configured to reducelevels of communication interference caused by the switched-mode powersupply.
 14. The Internet-enabled appliance of claim 11, whereinmodification of the operating mode of the switched-mode power supplyincludes at least one of disabling harmonic spreading of theswitched-mode power supply, reducing a power output of the switched-modepower supply, and suspending frequency fluctuation of the switched-modepower supply.
 15. The Internet-enabled appliance of claim 14, whereinreducing a power output of the switched-mode power supply includessynchronizing power reduction with a determined pattern detected in theInternet communications.
 16. A power line modem arranged to communicateInternet-based data, comprising: a transmission detector configured todetect a preamble of an Internet-based communication signal received ona 50 to 60 Hz alternating current (AC) power line; and an outputcoupleable to a switched-mode power supply that receives power on the 50to 60 Hz AC power line, the output arranged to automatically direct theswitched-mode power supply to modify an operating mode after detectionof the preamble.
 17. The power line modem of claim 16, wherein modifyingthe operating mode includes setting a switching behavior of theswitched-mode power supply.
 18. The power line modem of claim 16,wherein modifying the operating mode includes synchronizing themodification of the operating mode with a determined pattern detected inthe Internet-based communication signal.
 19. The power line modem ofclaim 16, wherein modifying the operating mode includes directing a loadcoupled to a DC output of the switched-mode power supply to reduce powerconsumption.
 20. The power line modem of claim 16, wherein the powerline modem communicates data according to a HomePlug protocol.